Rotor Field Winding Fault Detection via Stator Magnetic Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional short circuit detection devices for rotating electrical machines require complex and large-sized structures to accommodate a movable probe and withstand vibration from cooling air, making them bulky and difficult to implement effectively.
Innovation Solution
A short circuit detection device with a magnetic detector placed inside a stator, opposed to the field winding of a rotor, and a signal processing device that decomposes voltage signals into frequency components, reduces specific frequency components, and generates a difference waveform to detect short circuits and estimate their position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a movable probe mechanism is used to detect field winding short circuits, then detection capability is improved, but device complexity and size increase
Solution Approach 1:
The patent replaces the mechanical probe system with a magnetic detector that senses magnetic flux changes. Instead of physically contacting or sliding the probe against the rotor, the system uses a stationary magnetic detector to detect changes in magnetic flux caused by field winding short circuits, thereby eliminating complex mechanical mechanisms while maintaining detection capability
Solution Approach 2:
The patent introduces magnetic flux as an intermediary to transfer information about field winding conditions. The magnetic detector detects changes in magnetic flux, which serves as a mediator between the field winding and the detection system, allowing indirect but accurate detection without direct mechanical contact
2Reliability
If a probe structure with sufficient strength against vibration is designed, then reliability under cooling air flow is improved, but device size and complexity increase
Solution Approach 1:
The patent eliminates the need for mechanically robust probe structures by replacing the mechanical detection system with a magnetic sensing system. The magnetic detector remains stationary and does not require vibration resistance mechanisms, as it detects electrical/magnetic signals rather than requiring physical contact under vibration
Solution Approach 2:
The patent extracts the detection function from the mechanical probe structure and places it in a stationary magnetic detector. This separates the detection capability from the mechanical support structure, allowing the detector to be small and simple while the rotor and cooling system operate independently
3Measurement precision
If signal processing with frequency component reduction is implemented, then detection accuracy is improved, but signal processing complexity increases
Solution Approach 1:
The patent changes the parameter domain by transforming time-domain voltage signals into frequency-domain representations through Fourier transformation. This parameter change allows selective filtering of specific frequency components (odd and even orders) that correspond to short circuit signatures, improving detection accuracy through frequency-based differentiation
Solution Approach 2:
The patent segments the voltage signal into distinct frequency components (odd-order and even-order harmonics) and processes them separately. By dividing the signal processing into discrete frequency bands and applying different reduction criteria to each, the system achieves precise short circuit detection while maintaining organized and manageable processing complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device reliably detects short circuits in the field winding of a rotor while maintaining a small-sized and simple configuration, improving detection accuracy and reducing the risk of erroneous detection.
Implementation Method 1
a probe having a pickup coil therein... detects by a probe having a pickup coil therein... voltage signal which is the signal from the magnetic detector
Data Source
AI summary
A short circuit detection device for a rotating electrical machine includes: a signal processing device including a signal acquisition unit, a signal decomposing unit, a specific frequency component reducing unit, a signal conversion unit, and a short circuit detection unit; and a magnetic detector placed inside a stator, and detects short circuit of a field winding. The signal decomposing unit decomposes a voltage signal from the signal acquisition unit into a plurality of frequency components having different orders. The specific frequency component reducing unit reduces frequency components for odd-number orders and frequency components for even-number orders higher than a threshold less than a fundamental order of a slot harmonic. The signal conversion unit performs conversion to a voltage signal. The short circuit detection unit generates a difference waveform between voltage signals corresponding to magnetic poles, and detects short circuit of the field winding and a short circuit position thereof.